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Session C7: Inertial Measurement Unit (IMU)

LN200HP (Compacted High Performance IMU) with High Gyro Bandwidth, Low Quantization Noise, ARW, and Gyro Bias Error
Steven Kim, Daniel Tazartes, Greg Zimmerman, Northrop Grumman
Alternate Number 3

Fiber optic technology, initially driven by the telecommunications industry emerged as a leading candidate for the next generation of optical gyroscope. Coherent light is launched simultaneously in a clockwise and counter-clockwise direction through a fiber optic coil and recombined upon exit. When the coil is stationary, both beams experience the same optical path leading to constructive interference. When the coil is rotating, the Sagnac effect causes one beam to experience a longer optical path length than the other, resulting in a phase difference between them proportional to angular rate, and a corresponding decrease in intensity. They are scalable since their performance is driven by the product of coil length and diameter. However, there is a disadvantage to increasing coil length. As coil size increases to improve gyro performance, the coil becomes more sensitive to mechanical vibration and temperature gradients.
In 2016, the team built the first prototype LN200 system to significantly reduce Quantization Noise, ARW, and Gyro Bias Error by using the latest Northrop Grumman iFOG technology while maintaining the existing LN200 system size and interface. In 2017, this configuration became known as LN200HP. The LN200HP (Ultra-Low Profile Gyro) system successfully demonstrated approximately 7x improvement in Angle Random Walk (ARW) and approximately 7x improvement in gyro bias from the standard LN200 gyros without increasing the coil size.



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